1. Field of the Invention
The present invention relates to a controlling equipment, which serves to keep a period at a proper length, in an electronic equipment incorporating an oscillator that operates intermittently. The period is a period where a circuit for performing predetermined processing on a signal generated by the oscillator is to operate or a period which is prior to the above period and where power is to be supplied to the oscillator. The invention also relates to a radio equipment that incorporates such a controlling equipment and forms a predetermined radio transmission path.
2. Description of the Related Art
With deregulation of the market and intense competition between many manufacturers of terminal equipments and between a plurality of communication carriers, the number of subscribers who make use of mobile communication systems have been increasing rapidly.
Among various terminal equipments, portable terminal equipments, in particular, are strongly required to be not only compact and light but also capable of continuously waiting for a termination call for a long time without recharging of a battery.
That is, manufacturers of terminal equipments have been eagerly researching techniques that realizing saving of power consumption without increasing the size and weight because the price performance of a portable terminal equipment are dependent on such techniques.
FIG. 9 shows the configuration example of a conventional terminal equipment where power consumption is reduced during awaiting state.
As shown in FIG. 9, the output of a standard oscillator 71 is connected to the feeding point of an antenna 74 via a phase lock oscillator 72 and a radio interfacing part 73, which are cascaded. The output of the low-frequency oscillator 75 is connected to the clock terminal of a controlling equipment 76. The controlling equipment 76 is provided with a processor (not shown), and the control terminals of the standard oscillator 71 and the phase lock oscillator 72 are connected to predetermined output ports of the processor. The input/output terminals of the radio interfacing part 73 are connected to other particular input/output ports, respectively, of the controlling equipment 76 (processor).
In the terminal equipment having the above configuration, the low-frequency oscillator 75 constantly generates a clock signal of 32 kHz, for example, and supplies it to the controlling equipment 76.
The controlling equipment 76 operates under the initiative of the processor and has first and second frequency dividers (now shown).
The first frequency divider constantly generates a first signal (see FIG. 10A) having a cycle of 720 ms (=(1/(32xc3x97103))xc3x972,304) and a duty factor of {fraction (1/36)} (=20 ms/720 ms=640/23,040), for example, by frequency-dividing the above-mentioned clock signal.
By frequency-dividing the above-mentioned clock signal parallel with the frequency division by the first frequency divider, the second frequency divider constantly generates a second signal (see FIG. 10B) that satisfies all the following conditions, for example:
Rises before the first signal by a maximum time t that is necessary for the standard oscillator 71 to initiate a stationary operation.
Falls at the same as the first signal.
The controlling equipment 76 causes the phase lock oscillator 72 to operate only in a first period while the first signal has a logical value xe2x80x9c1xe2x80x9d and causes the standard oscillator 71 to operate only in a second period while the second signal has a logical value xe2x80x9c1.xe2x80x9d
The standard oscillator 71 starts operating at the start point of the second period, and generates, with predetermined accuracy, a reference signal whose frequency is equal to a predetermined frequency (e.g., 16 MHz) after a lapse of the above-mentioned maximum time t in the second period.
The phase lock oscillator 72 starts operating at the start point of the first period. That is, the phase lock oscillator 72 supplies a local frequency signal having a regular frequency to the radio interfacing part 73 in a stable manner by performing frequency synthesis on only the effective, stable reference signal.
The controlling equipment 76 takes initiative in determining operating conditions of the radio interfacing part 73 under a channel control that is performed by the above-mentioned processor according to a stored program control method.
Incidentally, in the above conventional example, the time difference between the rise of the first signal and the rise of the second signal is set at the above-mentioned maximum time t where stable supply of the above-mentioned local frequency signal is enabled, because the time t necessary for the standard oscillator 71 to initiate a stationary operation varies depending on the environmental conditions such as the temperature.
Further, the maximum time t has to include a predetermined margin to accommodate dispersion etc. of the components of the standard oscillator 71.
As a result, the standard oscillator 71 operates for more than a periods where the above-mentioned local frequency signal should be supplied.
The above problems can be solved by using any of the following techniques:
A first technique in which the time necessary for an initiation of a stationary operation is actually measured for each standard oscillator 71 incorporated in an equipment and the measured time or a possible maximum value of the measured time due to a deviation etc. of the environmental conditions is used instead of the above-mentioned maximum time t.
A second technique in which a highly stable crystal oscillator with high accuracy and stability in oscillating frequency is used as the standard oscillator 71.
However, where the first technique is applied, a large amount of man-hour is necessary to actually measure the time required for initiation of stationary operation of each standard oscillator 71, to reflect a measurement result, etc. on the power controlling equipment 76.
Where the second technique is used, there will be a high possibility of an increase in the hardware cost, the mounting space, and power consumption.
In practice, it is difficult to realize either of the above techniques which have a factor of preventing price reduction or downsizing required for mass-produced terminal equipments.
An object of the present invention is to provide a controlling equipment and a radio equipment capable of realizing a reduction in useless power consumption of an oscillator that intermittently operates.
Another object of the invention is to reliably and stably reduce the power consumption and the costs including the running cost of an equipment or a system to which the invention is applied, and to highly maintain the reliability of such an equipment and system without deteriorating performance, characteristics, or service quality.
A further object of the invention is to properly and automatically set an instant at which an oscillator initiates operation in accordance with its characteristics, in an equipment comprising a circuit such as a receiving part that operates according to a signal generated by the oscillator intermittently oscillating.
The invention provides a controlling equipment where an actual initiation time taken for an initiation of stationary operation of an oscillator is monitored and power is started to be supplied to the oscillator at an instant that precedes, by a length of the initiation time, an instant where a circuit is to initiate its operation. The circuit is provided subsequently to the oscillator and is to intermittently operate.
In this controlling equipment, the oscillator operates in a stationary state before an instant where the circuit starts a stationary operation, thereby preventing useless power consumption of the oscillator before the instant.
According to another aspect of the invention, there is provided a controlling equipment where a minimum value of the initiation time is given in advance to employ, as an actual initiation time, a larger one of the minimum value and an actually monitored initiation time.
This controlling equipment realizes power saving and cost reduction without performing complex arithmetic operations as long as the above minimum value is proper.
According to another aspect of the invention, there is provided a controlling equipment where: an average value of actually monitored initiation time is applied when the average value is constant; a value larger than the average value is applied when the average value increases; and a value smaller than the average value is applied when the average value decreases.
This controlling equipment attains power saving with high reliability without frequently or excessively varying the time required for an initiation of stationary operation of an oscillator due to a variation in the characteristics etc. of the oscillator.
According to still another aspect of the invention, there is provided a controlling equipment that monitors an initiation time.
This controlling equipment attains power saving with high reliability even in a case where the initiation time may vary frequently or rapidly.
According to yet another aspect of the invention, there is provided a controlling equipment where the sum of a monitored initiation time and a predetermined margin is used for determining an instant at which an oscillator starts.
This controlling equipment enables power saving and cost reduction without performing complex arithmetic operations as long as the margin is proper.
According to a further aspect of the invention, there is provided a radio equipment incorporating the controlling equipment which has the initiative of determining an instant at which an oscillator is to initiate an operation. The oscillator is to operate for intermittently receiving a signal coming from a base station.
This radio equipment makes it possible to highly reliably maintain power saving by intermittently receiving the above signal; to reduce the running cost; and to reduce the capacity of battery and increase the time for continuously waiting a call or enable flexible use of an added value, particularly in a case where the driving power is supplied from a battery,